with tight 1D exciton confinement, demonstrating highly promising properties by their possible design of heterostructures. [1][2][3] The size-and shape-dependent properties of these materials alongside with various electronic structures enable them for a vast range of optoelectronic applications [4] including light-emitting diodes (LEDs), [5,6] luminescent solar concentrator, [7] photodetectors, [8] lasers, [9][10][11] and photocatalysts. [12] These NPLs offer such advantages over their spherical counterparts, colloidal quantum dots (CQDs), as they possess giant oscillator strengths, [13,14] larger absorption crosssections, [15][16][17] and enhanced molar extinction coefficients. [18] While inhomogeneous broadening is a major drawback of CQDs, NPLs with constant ensemble thickness, exhibit much narrower emission bandwidth. [19,20] CdSe NPLs are among the most studied CQWs, offering a suitable platform as a base material to further design and synthesize complex heterostructures. In its zinc blend crystalline structure, increasing the thickness along [001] direction, normal to the basal planes, [21] can be performed mainly through one of the two strategies: i) One/two-pot synthesis of thick NPLs [22,23] Extending the emission peak wavelength of quasi-2D colloidal quantum wells has been an important quest to fully exploit the potential of these materials, which has not been possible due to the complications arising from the partial dissolution and recrystallization during growth to date. Here, the synthetic pathway of (CdSe/CdS)@(1-4 CdS/CdZnS) (core/crown)@(colloidal atomic layer deposition shell/hot injection shell) hetero-nanoplatelets (NPLs) using multiple techniques, which together enable highly efficient emission beyond 700 nm in the deep-red region, is proposed and demonstrated. Given the challenges of using conventional hot injection procedure, a method that allows to obtain sufficiently thick and passivated NPLs as the seeds is developed. Consequently, through the final hot injection shell coating, thick NPLs with superior optical properties including a high photoluminescence quantum yield of 88% are achieved. These NPLs emitting at 701 nm exhibit a full-width-at-half-maximum of 26 nm, enabled by the successfully maintained quasi-2D shape and minimum defects of the resulting heterostructure. The deep-red light-emitting diode (LED) device fabricated with these NPLs has shown to yield a high external quantum efficiency of 6.8% at 701 nm, which is on par with other types of LEDs in this spectral range.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smll.202106115.

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Synthesis of star‐shaped polystyrene (PS) and poly (methyl metachrylate) (PMMA) containing a polyhedral oligomeric silsesquioxane (POSS) core are fabricated by combination of atom transfer radical polymerization (ATRP) and copper (I) catalyzed azide‐alkyne cycloaddition (CuAAC) click reaction techniques. The synthetic route proceeds in two steps; firstly, clickable alkyne‐end functionalized polymeric arms and a POSS‐(N3)8 core are prepared independently by arm‐first approach using ATRP and nucleophilic substitution reaction of octa‐(3‐chloropropyl) silsesquioxane POSS‐(Cl)8 with sodium azide. Finally, the CuAAC click reactions between inorganic‐organic hybrid core POSS‐(N3)8 and alkyne functionalized PMMA and PS arms provide the targeted star‐shaped polymers. Their chemical structures and molecular characteristics are clearly confirmed by FT‐IR, 1H‐NMR, and GPC analyses. The obtained polymers are utilized as insulators for organic field effect transistors (OFETs) using perylene as an active n‐type organic semiconductor. Compared with linear PMMA and PMMA‐POSS, the POSS‐(PMMA)8 exhibited better output and transfer characteristics for the OFET device.

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